(EFCore & Identity) 在上一个操作完成之前，在此上下文中启动了第二个操作

Question

I get this error from a method that is called from blazor server side component:

System.InvalidOperationException: A second operation started on this context before a previous operation completed. 
This is usually caused by different threads using the same instance of DbContext. 
    Microsoft.EntityFrameworkCore.Internal.ConcurrencyDetector.EnterCriticalSection()
       at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.AsyncQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
       at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
       at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
       at BlazorStore9.Business.Account.GetProfileAndRoles(Int32 profileID) in 

from this method:

 public async Task<EditBlogUserModel> GetProfileAndRoles(int profileID)
    {
        Profile profile = await context.Profiles.AsNoTracking().FirstOrDefaultAsync(p => p.Id == profileID);
        if (profile == null)
            return null;
        //context.Entry(profile).State = EntityState.Detached;
        AppUser user = null;
        try
        {
            user = await userManager.FindByNameAsync(profile.UserName);
        }
        catch (Exception ex)
        { }
        var roles = await roleManager.Roles.ToListAsync<IdentityRole>();
        List<string> allRoles = roles.Where(r => r.Name != "Administrators" && r.Name != "Editors" && r.Name != "Users")
            .Select(r => r.Name).ToList<string>();
        IList<string> userRoles1 = await userManager.GetRolesAsync(user);
        List<string> userRoles = userRoles1.Where(r => r != "Administrators" && r != "Editors" && r != "Users").ToList<string>();
        List<RoleModel> rolesModel = new List<RoleModel>();
        var keyValuePairs = configuration.GetSection("BlogRoles").GetChildren();
        foreach (string role in allRoles)
        {
            if (userRoles.Find(r => r == role) != null)
            {
                rolesModel.Add(new RoleModel() { Text = keyValuePairs.FirstOrDefault(kvp => kvp.Key == role).Value, Value = role, Checked = true });
            }
            else
            {
                rolesModel.Add(new RoleModel() { Text = keyValuePairs.FirstOrDefault(kvp => kvp.Key == role).Value, Value = role, Checked = false });
            }
        }
        return new EditBlogUserModel()
        {
            ProfileID = profileID,
            Name = profile.UserName,
            Email = profile.Email,
            Roles = rolesModel
        };
    }

I tried to convert Tolist() to ToListAsync() and the whole method async, But I still get this error.

Caller component that its name is EditBlogUser.razor and is nested some levels inside other components:

protected override async Task OnInitializedAsync()
{
    await base.OnInitializedAsync();


    Model = await account.GetProfileAndRoles(ProfileID);
   

    StateHasChanged();

}

Startup file:

services.AddDbContext<AppDbContext>(options =>
        options.UseSqlServer(
            Configuration["Connections:AppConnection:ConnectionString"]), ServiceLifetime.Transient);

        services.AddDbContext<IdentityContext>(options =>
            options.UseSqlServer(
                Configuration["Connections:IdentityConnection:ConnectionString"]), ServiceLifetime.Transient);

How to get this to work?

Answer 1

In blazor component that Lists the User Profiles, I put each component in a Bootstrap Popup, But I call the GetProfileAndRoles method from component's OnInitializedAsync lifecycle method, This caused all popup components to initialize when parent component loads, So I moved the Initialization code that calls GetProfileAndRoles method to popup's Click event, Now the component initializes only with a click event. And it is working.